Generally, an MCU (motor control unit) is used to control an induction motor or a synchronous motor that is used in an electric vehicle and a hybrid vehicle. For this, a coordinate system is established according to a position of flux. Accordingly, a resolver is used to read an absolute position of a motor rotator.
A resolver is a kind of transformer to transmit an excitation voltage to a first side winding (input side), and if an axis is rotated, a magnetic coupling coefficient is transformed and a voltage that varies the amplitude of a carrier is generated in a second side winding (output).
The winding is arranged such that the voltage varies along sine and cosine curves based on the rotation angle. Accordingly, the rotation angle of the resolver can be detected by reading the carrier amplitude of the sine output and the cosine output.
A resolver that is operated according to the above principle senses speed and phase data of the motor and transfers the position data of the motor rotator to the MCU, and these are used for generating a torque order and speed order.
However, an offset or error can be generated while mounting the resolver, so an accurate position of the rotator of the motor cannot be detected because of the error or the offset, and this causes the motor to be abnormally operated.
Accordingly, as a method for compensating the sensing error, a measuring instrument such as an oscilloscope is used to analyze a waveform of the resolver and line-to-line counter-electromotive force of the motor and then an offset value for the sensing error is compensated.
This method is performed by a manual operation of an operator, so the time required is increased, the amount of work is increased, and all vehicles have to be compensated. Also, the compensation value can vary according to the skill level of the operator.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it can contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.